Globalsat ET-318 User Manual
環天衛星科技股份有限公司
PRODUCT USER MANUAL
GPS ENGINE BOARD
ET-318
Version 1.0
GlobalSat Technology Corporation
台北縣中和市建一路 186 號 16 樓(遠東世紀廣場)
16, No.186,Chien 1 Road, 235Chung Ho City,Taipei Hsien, Taiwan ,R.O.C.
Tel: 886-2-8226-3799(Rep.) Fax: 886-2-8226-3899
Web: www.globalsat.com.tw E-mail: service@globalsat.com.tw
Features:
SiRF starⅢ high performance GPS Chip Set
Very high sensitivity (Tracking Sensitivity: -159 dBm)
Extremely fast TTFF (Time To First Fix) at low signal level
Compact size (15.2mm * 14 mm * 2.8mm) suitable for space-sensitive application
One size component, easy to mount on another PCB board
Support NMEA 0183 and SiRF binary protocol
Specification:
General
Chipset SiRF StarⅢ
Frequency L1, 1575.42 MHz
C/A code 1.023 MHz chip rate
Channels 20 channel all-in-view tracking
Sensitivity -159 dBm
Accuracy
Position 10 meters, 2D RMS
5 meters, 2D RMS, WAAS enabled
Velocity 0.1 m/s
Time 1us synchronized to GPS time
Datum
Default WGS-84
Acquisition Time
Reacquisition 0.1 sec., average
Hot start 1 sec., average
Warm start 38 sec., average
Cold start 42 sec., average
Dynamic Conditions
Altitude 18,000 meters (60,000 feet) max
Velocity 515 meters /second (1000 knots) max
Acceleration Less than 4g
Jerk 20m/sec **3
Power
Main power input 3.3V +- 5% DC input
Power consumption 42mA (Continuous mode)
36mA (Trickle power mode
Interface
Dimension 15.2mm * 14 mm * 2.8mm
Baud rate 4,800 to 57,600 bps adjustable
Output message SiRF binary or
NMEA 0183 GGA, GSA, GSV, RMC, VTG, GLL
GPS Passive (or Active )Antenna Specification(Recommendation)
Frequency: 1575.42+2 MHz
Axial Ratio: 3 dB Typical
output Impedance: 50Ω
Polarization: RHCP
Output VSWR: 1.5 Max.
Active option
Low Noise Amplifter:
Amplifier Gain :20~26dB Typical
Output VSWR: 2.0 Max.
Noise Figure: 2.0 dB Max.
Environmental
Operating Temperature -40℃ to +85℃
Storage Temperature: -40℃ to +85℃
Pin Assignment
Pin Signal Name I/O Description
1 GND G Analog Ground
2 RF_IN RF GPS Signal input
3 GND G Analog Ground
4 NRESET I Reset (Active low)
5 VCC_IN PWR DC Supply Voltage input
6 VBAT PWR Backup voltage supply
7 RXB I Serial port B
8 TXB O Serial port B
9 GND G Analog Ground
10 BOOTSEL Boot mode
11 TXA O Serial port A
12 RXA I Serial port A
13 GPIO1 I General –purpose I/O
14 GPIO14 I General –purpose I/O
15 TIMEMARK O One pulse per second
16 GPIO13 I General –purpose I/O
17 GPIO15 I General –purpose I/O
Definition of Pin assignment
VCC_IN
This is the main DC supply for a 3.3V +- 5% DC input power module board.
GND
GND provides the ground for digital pa
BOOTSEL
rt.
Set this pin to high for programming flash.
RXA
This is the main receiver channel and is used to receive software commands to
the
board from SIRFdemo software or from user written software.
PS:
RXB
Pull up
if
not used.
This is the auxiliary receiving channel and is used to input differential
corrections
Pull up
PS:
TXA
This is the main transmitting channel and is used to output
navigation and measurement data to SiRFdemo or user written software.
TXB
to
the board to enable DGPS navigation.
if
not used.
For user’s application (not currently used).
RF_IN
This pin receiver signal of GPS analog .due to the RF characteristics of the
signal
the design has to certain criteria. The line on the PCB from the
antenna(or
PPS
This pin provides one pulse-per-second output from the board,
which is synchronized to GPS time. This is not available in Trickle Power
antenna connector) has to be a controlled microstrip line at 50Ω
mode
.
Backup battery (V_BAT)
This is the battery backup input that powers the SRAM and RTC when main
power is removed. Typical current draw is 15uA. Without an external backup
battery, the module/engine board will execute a cold star after every turn on.
To achieve the faster start-up offered by a hot or warm start, a battery backup
must be connected. The battery voltage should be between 2.0v and 5.0v.
TIMEMARK
This pin provides one pulse-per-second output from the
board, which is synchronized to GPS time. This is not available in Trickle
Power mode
GPIO
Functions
Several I/Os are connected to the digital interface connector
for custom applications
Application Circuit
Antenna
.
1
..
LNA
3.3V
BATTERY
C1
1U
1 2
C2
0.1U
1 2
R46
1 2
560R
.
VCC_RF
R5
1 2
21
SAW FI LTER
option
1
3
RB715F
.
50 ohm m icros trip line
2
RESET
RXB
TXB
1
2
3
4
5
6
7
8
U1
GND
RF_IN
GND
NRESET
VCC_I N
VBAT
RXB
TXB
GPS
GPIO15
GPIO13
TI MEMARK
GPIO14
GPIO1
RXA
TXA
BOOTSEL
GND
17
16
15
14
13
12
11
10
9
GPIO15
GPIO13
TI MEMARK
GPIO14
GPIO1
RXA
TXA
BOOTSEL
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